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I just finished rebuilding my d16z6. It has about 50 miles on it. It has a brand new ACL race oil pump. Main bearing clearances are .0018-.002 and rods are about .0024-.0025. I'm running 10w-40 and my oil pressure is a little lower than I would like it. Its about 90 psi on cold idle, but after it gets hot, it hovers around 9-15 psi. 3k rpm is about 65-75. It's not turbo yet, but I plan to turbo it in the near future. I'm worried that I'm gonna have issues down the when the oil gets extra hot from the turbo. My machinist said to run either 10w-40 or 20w-50, but how much of a difference will the thicker oil make? Any ideas for what the problem could be? Should I be worried?
 

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BATSLOMAN GIVES NO FUCKS.
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D16Z6 Oil Pressure Specs ???

According to my Helms Manual 8-6,

When the oil is at 176F(80C) the specs are:
@ idle 10psi minimum
@ 3K rpm 50psi minimum
It does not give a spec at WOT though, and only minimum allowable oil pressures so I can't tell you if it's too high.
 

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BATSLOMAN GIVES NO FUCKS.
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it tells you what the bare minimum of "safe" is.

does high flow = volume or pressure.
 
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Discussion Starter #5
it tells you what the bare minimum of "safe" is.

does high flow = volume or pressure.
The higher volume of oil should in turn increase oil pressure. I'm just curious, in your signature, it says you have a turbo d16z6. What are your oil pressure numbers?
 

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BATSLOMAN GIVES NO FUCKS.
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whatever the stock pump puts out.....
 
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what kind of gauge are you testing the pressure with?
if more than 4 psi at idle who gives a shit..
why is your rod clearance so loose?

I run 15w40

did your pump come with a spec sheet?
 

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Discussion Starter #8
what kind of gauge are you testing the pressure with?
if more than 4 psi at idle who gives a shit..
why is your rod clearance so loose?

I run 15w40
It's a cheapo Jegs electric oil pressure gauge. My clearances with STD bearings were .0024-.0025 for the rods and .0029 - .003 with the mains. I didn't want such a small clearance on the rods so I decided to just buy .025mm oversized bearings for the mains and keep the STD for the rods. Next oil change I'm going to put 20w-50 in it.

ACL RACE PUMP:
  • Engine RPM - 600 - OE Oil Pump - 5.6 L/MIN - ACL Orbit Performance Oil Pump - 6.83 L/MIN
  • Engine RPM - 3000 - OE Oil Pump - 27.3 L/MIN - ACL Orbit Performance Oil Pump - 33.3 L/MIN
  • Engine RPM - 5000 - OE Oil Pump - 32.7 L/MIN - ACL Orbit Performance Oil Pump - 39.9 L/MIN
 

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BATSLOMAN GIVES NO FUCKS.
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liter per minute does not compute to psi......
 
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liter per minute does not compute to psi......
I understand, but assuming you have the same oil clearances on 2 separate engines, one with OEM and one with the ACL oil pump, the ACL would have higher oil pressure because of its larger amount of flow causing more pressure buildup at the bearings.
 

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I like to see 80psi at high rpm even with hot oil. I like to see 80 psi at 1000rpm with cold oil.
 

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1993 Del Sol
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whatever the stock pump puts out.....
I there with you, I have a d16z6 turbo with a stock type oil pump and it was all done less than 200 miles ago, I ran 15w40 initially and now have 5w40. I can't tell you my exact oil pressure because I haven't hooked up a gauge either.
What I'm trying to get at is if your engine is happy then chill a bit, unless you have the numbers from your pre rebuild and you're now way lower across the board. I have a lunatic buddy who rebuilt a y8 2 years ago and he's been using 5w20 in Florida despite my warnings and he plans on going turbo! He has gauges.. I can ask him what he gets if you'd like.
 

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Discussion Starter #13
I there with you, I have a d16z6 turbo with a stock type oil pump and it was all done less than 200 miles ago, I ran 15w40 initially and now have 5w40. I can't tell you my exact oil pressure because I haven't hooked up a gauge either.
What I'm trying to get at is if your engine is happy then chill a bit, unless you have the numbers from your pre rebuild and you're now way lower across the board. I have a lunatic buddy who rebuilt a y8 2 years ago and he's been using 5w20 in Florida despite my warnings and he plans on going turbo! He has gauges.. I can ask him what he gets if you'd like.
Yeah that would be nice to know. When I go turbo, i'm going to have to drop the pan anyway to put in an oil return, so Ill take a look at the pickup and see if there's any shit in it. I may or may not take off the oil pump to see if any gasket maker is blocking the pump, but I feel like that would be a waste of time because I went pretty easy on the gasket maker. Other than that, I guess all I can do is put thicker oil in it and hope my pressure is acceptable. If not, I might put some oversized bearings on the rod journals. That would put my clearances at .0014-.0015 on the rods.
 

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If you're going to run oversized bearings you're going to have to get the crank turned.

Okay i just spoke to him, he said he sees 100psi upon start up, 40psi upon warm up, and about 30-40 while driving. He said his drops to 0psi (i am not making this up) sometimes at idle. Again, he is a lunatic and is running 5w20 in a d16y8! So take from that what you will.
 

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I've been meaning to post lately, just now got around to doing so!

OP, that is kinda loose on the rod bearings no? Spec for Z6 crank mains is 0.0008- 0.0016", rods are 0.0008" - 0.0015".

With your mains being closer to 0.002" and rods even looser at 0.0024 - 0.0025", I would expect a drop in oil pressure. The fact that you have a high volume oil pump means that you will be moving more oil volume up to the bearings, which is good, but restriction is what causes pressure. Because mains and rods are significantly looser than spec, I wouldnt expect oil pressure to match factory readings, i would expect them to be a bit under even with heavier oil and HVOP.

I have .0015 on my crank, and 0.001 on my rods (D16Y8). I see 80+ PSI with 5w40 rotella T6 on start up 1200RPM, about 50psi when ECT reaches 160 degree and idle drops to 950RPM.

After beating on it for about 30 mins in 85-90 degree ambient temps, hot idle pressure is around 12-18PSI and hot cruise in 5th at about 3K is about 50PSI. I still see 80+ with hot oil above 4500RPM.

I also run an external oil cooler setup, it helped me pick up 8-10PSI oil pressure all around when hot compared to without it.
 

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Discussion Starter #16
If you're going to run oversized bearings you're going to have to get the crank turned.

Okay i just spoke to him, he said he sees 100psi upon start up, 40psi upon warm up, and about 30-40 while driving. He said his drops to 0psi (i am not making this up) sometimes at idle. Again, he is a lunatic and is running 5w20 in a d16y8! So take from that what you will.
Why would I need the crank turned. I would buy .001 oversized bearings putting me near .0015 opposed to .0025. Damn I would never want to run my engine on that low of oil pressure.
 

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Discussion Starter #17
I've been meaning to post lately, just now got around to doing so!

OP, that is kinda loose on the rod bearings no? Spec for Z6 crank mains is 0.0008- 0.0016", rods are 0.0008" - 0.0015".

With your mains being closer to 0.002" and rods even looser at 0.0024 - 0.0025", I would expect a drop in oil pressure. The fact that you have a high volume oil pump means that you will be moving more oil volume up to the bearings, which is good, but restriction is what causes pressure. Because mains and rods are significantly looser than spec, I wouldnt expect oil pressure to match factory readings, i would expect them to be a bit under even with heavier oil and HVOP.

I have .0015 on my crank, and 0.001 on my rods (D16Y8). I see 80+ PSI with 5w40 rotella T6 on start up 1200RPM, about 50psi when ECT reaches 160 degree and idle drops to 950RPM.

After beating on it for about 30 mins in 85-90 degree ambient temps, hot idle pressure is around 12-18PSI and hot cruise in 5th at about 3K is about 50PSI. I still see 80+ with hot oil above 4500RPM.

I also run an external oil cooler setup, it helped me pick up 8-10PSI oil pressure all around when hot compared to without it.
I wanted to run a wider clearance to keep the oil cooler and to allow more crankshaft flex, but I definitely should have put oversized bearings on the rods journals too. I will probably end up doing that.
 

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I wanted to run a wider clearance to keep the oil cooler and to allow more crankshaft flex, but I definitely should have put oversized bearings on the rods journals too. I will probably end up doing that.
Okay, I have never before heard of running oversized bearings without doing the machine work to properly compensate, my ignorance, it never came up in class. By how much would it allow your engine oil temperature? (Degrees?) I would have never thought of that... I'd just install an oil cooler. Again, learn something new daily.
 

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Tight fitting rotating parts are not only necessary for oil pressure, but for spreading out the forces being exerted. Wide or loose tolerances allow excessive wear to take place due to parts being allowed to slam into each other with more force and velocity than would otherwise be allowed.

Oil is designed to stand up to heat between moving parts when tolerances are at spec. Cooling of the main reservoir is what manages the heat, either by direct cooling methods of the oil pan, or through external cooling approaches. Always spec oil clearances per the OEM manual, unless you have a very specific need and/or the R&D to back up such a deviation from spec.
 

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Okay, I have never before heard of running oversized bearings without doing the machine work to properly compensate
You are correct, its uncommon to just slap in oversized bearings and roll haha, unless you had prior knowledge of the crank being turned.

Machining or polishing the crank for new bearings is assurance the journals are straight and flat, and a standard rebuilding practice, because the new bearings going in will be very flat. Even if the crank seems flat, it could vary if its been used and abused before, meaning your measurements of oil clearance might show one reading in one spot, and another somewhere else.

Keeping things even and flat across the board is usually the goal when choosing oversized bearings. The machinist will cut the crank the right amount to stay within OEM spec oil clearance while using the oversize bearings.

Rule of thumb: if the crank has never been turned before, yet your oil clearances are way out of spec and requires the thought of oversized bearings to make up the slack, the crank needs to be turned, and the proper oversized bearings selected to achieve the proper oil clearance.

Just slapping in oversize bearings on a crank to bandaid oil clearances is exactly that, a bandaid, with no guarantee of flatness. It honestly should be turned at the machine shop, and oil clearances restored the correct way, unless of course you have prior knowledge of the crank being turned and it hasn't been used much.

My 2 cents :)
 
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